Individuals with ADHD are at markedly high risk for increased substance use and Substance Use Disorder (SUD; Barkley et al., 2004; Charach et al, 2011; Derefinko & Pelham, in press; Lee et al., 2011; Molina & Pelham, 2003; Sibley et al., 2011). They have high rates of substance use across a wide range of substances, including illicit drugs, alcohol, and cigarettes (Arias et al., 2008; Molina & Pelham, 2003; Szobot et al., 2007), and are at risk for early onset of substance use behaviors and disorders (Arias et al., 2008; Milberger et al.,1997; Molina & Pelham, 2003). Importantly, these substance use problems do not abate over time; among individuals with adult ADHD, rates of substance use disorders approach 40% (Kalbag & Levin, 2005; Biederman et al., 1995), suggesting the need for early intervention. However, treatment of ADHD and substance use concurrently presents a number of problems for clinicians, including poor treatment adherence, lack of treatment progress, and impaired achievement of treatment goals, (Carroll & Rounsaville, 1993; Levin et al., 2004; Wise et al., 2001). Given these barriers, it is clear that future prevention and intervention development should follow the guidelines provided by the current literature on both ADHD and substance use treatment. Several psychosocial interventions for teens with SUD are well-established (Waldron & Turner, 2008; Winters & Leitten, 2007). However, typical studies that have examined efficacy of substance use interventions have conducted only secondary analyses to see if comorbid psychiatric diagnoses moderate outcome. There have been no controlled evaluations of how comorbid ADHD affects the efficacy of early intervention for early substance use. Given the strong evidence for the negative trajectory for individuals with co-occurring ADHD and substance use initiation, our goal is to conduct a controlled examination of a brief, early intervention for substance use (BEI; Teen Intervene, Winters & Leitten, 2007) modified for adolescents with ADHD by using the evidence from both treatment literatures. Importantly, this intervention will address individuals who have initiated substance use, but do not yet meet criteria for an SUD. Although brief interventions have been found to be effective in other populations, their efficacy in an ADHD population with emerging substance use remains uninvestigated. We expect BEI to be effective for some but not all ADHD teens, with lower rates of response than have been obtained with nonADHD populations. To better understand why some adolescents with ADHD and substance use initiation respond to BEI and others do not, we investigate the contributions of several cognitive, proximal and situational factors to treatment response. Finally, we will randomize non-responders to the BEI to three secondary treatment conditions (monitor only, parent training/adolescent cognitive behavioral therapy, and medication plus parent training/adolescent cognitive behavioral therapy) to determine the relative efficacy of these more intensive interventions for insufficient responders to brief treatment.